Skip to main content

Table 1 Baseline characteristics of 311,097 EPIC cohort participants

From: Reproductive factors and risk of hormone receptor positive and negative breast cancer: a cohort study

Study variables All women
(n = 311,097)
Age at recruitment (median, range) 51.1 (19.9-98.5)
Age end of follow-up (1st tumor) (median, range) 62.0 (21.2-102.4)
Years of follow up (median, range) 11.3 (0.0-16.7)
Menopausal status  
Premenopausal 108,084 (34.7)
Peri/Unknown 58,345 (18.8)
Postmenopausal 144,668 (46.5)
Age at menarche (median, range) 13.0 (8.0-20.0)
Age at menopause (median, range)1 50.0 (16.0-67.0)
Ever full-term pregnancy (yes, %) 255,877 (84.5)
Age at first full-term pregnancy (median, range)2 24.0 (12.0-56.0)
Time between menarche and first pregnancy (years) (median, range)2 11.0 (0.0-41.0)
Number of full-term pregnancies 2  
1 child 46,572 (18.8)
2 children 122,590 (49.4)
≥3 children 78,983 (31.8)
Breastfeeding (yes, %)2 200,885 (83.8)
Duration of breastfeeding, all pregnancies (months) (median, range)2,3 6.0 (0.2-286.4)
Age at last full-term pregnancy (median, range)2 29.0 (13.0-56.0)
Time since last full-term pregnancy (years) (median, range)2 22.9 (0.0-69.1)
Ever had an abortion (yes, %)4 87,130 (40.1)
Oral contraceptive (OC) use  
Never OC user 125,229 (41.4)
Past OC user 160,926 (53.2)
Current OC user 16,560 (5.5)
Age when you started using the pill (median, range)5 24.0 (8.0-50.0)
Duration of using the pill (years) (median, range)5 5.0 (1.0-15.0)
  1. 1In natural and surgically menopausal women only.
  2. 2In parous women only.
  3. 3In women who breast-fed only.
  4. 4Both spontaneous and induced abortions.
  5. 5In women who ever used OC.